This invention relates to a high speed plasma etching system, which is particularly adapted, among other possible uses, for semiconductor manufacture.
While many different types of plasma etching systems have been employed heretofore with some success, our contribution to the art is a new system, which is an improvement over such known ones.
The invention has as one of its objectives, the provision of a new and improved high speed etching system, which is adapted to employ a substantially totally insulated substrate table and other grounded surfaces, to thereby prevent short-circuit discharge current from passing around the edges of the wafer and greatly reducing the etching rate.
The invention provides as another of its objectives, a system of the character aforesaid, which employs a sintered or sintered-like porous electrode plate to provide uniform omnidirectional gas dispersal without local strong discharge regions.
Further, as still another objective thereof, the invention provides a high speed plasma etching system, which can accommodate silicon wafers that are not perfectly flat, as a result of the provision of clamping means to assure proper coupling between the wafer and the wafer support plate.
One further objective of the invention resides in the provision of a new and improved etching system, which utilizes low frequency excitation current, resulting in increased ion motion and other beneficial effects. The high ion energies resulting from these effects are important for increasing etch rates, anisotropy and selectivity for silicon oxide etching with a variety of fluorocarbon etch gases.
These and other advantages of the system of the invention, as compared to etching systems heretofore utilized for the above-stated purposes, will become apparent as the discussion proceeds.